The objective of this project is to investigate the pulmonary functional response to air pollutants in adolescent asthmatics, a group assumed to be "at risk". The form of air pollution studied will be sulfur dioxide (SO2) (0.5ppm) and sulfuric acid (H2SO4) (100 micrograms/cubic meters). The acute response to these pollutants will be studied both at rest and during intermittent moderate exercise. Control exposures will be to filtered air. All exposures will be at approximately 75% relative humidity and approximately 22 degrees C. The subjects will be exposed by mouth through a rubber mouth piece. Pulmonary functional measurements will be made while the subject is seated in a volume displacement body plethysmograph. The measurements will be total respiratory resistance, functional residual capacity, maximum flow a 50% and 75% of expired vital capacity and forced expiratory volume in one second. Exercise will be achieved by walking on a treadmill at a speed and elevation sufficient to increase minute ventilation approximately six times. The measurements will be recorded before, during and after exposure. The results will be compared to data from two previous experiments under similar conditions in our laboratory. One experiment studied in pulmonary functional response to acute exposure to 1ppm SO2 and a NaCl droplet aerosol in healthy non-smoking adults. The second experiment studied the response to 1ppm SO2 plus a NaCl droplet aerosol in a group of adolescent asthmatics.